1. Field of the Invention
The present invention relates generally to an improved test probe card structure, and more particularly to a probe card structure for testing integrated circuits. The probe card structure includes a connection circuit common plate connected between a test circuit board and a tester, whereby the test circuit board can be minified to lower the manufacturing cost of the probe card.
2. Description of the Related Art
After processed and formed and before packaged, the wafer of an integrated circuit needs to go through a chip probe (CP) process for testing the electrical functions of the chips of the wafer in every section so as to judge whether the quality of the chips in every section meets the requirement. Accordingly, the chips with poor electrical functions can be previously screened out without being packaged. In this case, the manufacturing cost can be lowered.
In the chip probe process, the wafer to be tested is placed on a tester for testing the integrated circuit. A probe card is installed on a test end of the tester. The probes of the probe card can precisely contact the pads or bumps on the surface of the wafer. The tester is composed of a computer operation system and a programmable signal generator and is program-writable. According to the differences between the circuit layouts of the wafer, different test programs are loaded into the tester. The tester transmits signals to the wafer through the probes of the probe card and receives the electronic feedback signals to show the wafer maps of the good products and defective products on the screen of the tester. Then the tester can automatically analyze and judge whether the functions of the chips are normal or abnormal.
The circuit layout of the chips of the wafer is designed according to the electrical functions of the chips to be achieved. Therefore, the chips can provide the electrical functions by means of the circuit layout. Each wafer necessitates a specific probe card and tester in adaptation to the electrical functions of chips of the wafer for successfully performing the test. Please refer to FIG. 1. A conventional probe card has a probe substrate 2a and a test circuit board 1a. The probe substrate 2a can be made of ceramic material and has a strength sufficient to support multiple probes 21a to abut against the wafer. In accordance with the electrical functions, the test circuit board 1a is divided into a substrate circuit connection section 11a directed to and electrically connected with the probe substrate 2a and a circuit extension section 13a formed around and electrically connected with the test circuit board 1a for electrically connecting with the tester. The test circuit board 1a has a test circuit 12a for electrically connecting with the substrate circuit connection section 11a and the circuit extension section 13a, in general, the bottom face of the substrate circuit connection section 11a of the test circuit board 1a is attached to the top face of the probe substrate 2a, whereby the test circuit 12a of the test circuit board 1a can be electrically connected to the probes 21a via the internal leads 22a of the probe substrate 2a. The circuit layout of the test circuit 12a is designed according to the electrical functions of the wafer to be tested so as to meet the electrical functions of the wafer. In other words, the circuit layout of the test circuit 12a in the probe card must be varied with the circuit layout of the wafer to be tested. Therefore, for testing different wafers with different circuit layouts and different electrical functions, the test circuit 12a of the probe card must be designed with a specific circuit layout, which cannot be commonly applied to other wafers with different circuit layouts.
The number of the test channels of the tester not only decides the test efficiency of the tester, but also decides the size and specification of the end of the tester for installing the test circuit board of the probe card. For example, the common testers on the market can be classified into 256-channel tester and 512-channel tester. The test capacity of the 512-channel tester is much higher than that of the 256-channel tester. Moreover, the specification of the test circuit board connectable to the 512-channel tester is larger than that of the test circuit board connectable to the 256-channel tester. Therefore, under the same technical condition and support, along with the increase of the required test capacity, there is inevitably a trend to manufacture the tester with a larger end for connecting with the test circuit board.
On the other hand, along with the continuous advance of the semiconductor techniques, the chips of the wafer have become smaller and smaller and the distribution density of the chips has become higher and higher. As a result, the number and arrangement density of the probes 21a of the probe card are inevitably increased. The test circuit board 1a of the conventional probe card has a circuit extension section 13a meeting the specification of the end of the tester, which is connectable with the test circuit board. The internal test circuit 12a is connected between the circuit extension section 13a and the substrate circuit connection section 11a to converge a large distribution range (size) to a small distribution range in adaptation to the electrical connection of top face of the probe substrate 2a. The circuit extension section 13a of the 256-channel probe card must meet the size or specification of the test circuit board connection end of the 256-channel tester for connection therewith and application thereto. Similarly, the circuit extension section 13a of the 512-channel probe card must meet the size or specification of the test circuit board connection end of the 512-channel tester, In addition, through the electrical connection of the test circuit 12a, the larger distribution range of the test circuit board connection end of the tester can be converged to the smaller size of the substrate circuit connection section 11a of the test circuit board 1a of the probe card. Then the circuit extension section 13a is electrically connected to the probes 21a via the probe substrate 2a. 
The test circuit 12a of the probe card has multiple outer connection terminals 121a extending to the top face of the circuit extension section 13a for electrically connecting with the test circuit board connection end of the tester. The circuit layout and number of the test circuit 12a, the substrate circuit connection section 11a, and the outer connection terminals 121a are varied with the change of the wafer to be tested. For example, in the case that the test circuit board connection end of the tester has 256 test terminals, the circuit layout of the outer connection terminals 121a of the probe card is changed and the number of the outer connection terminals 121a can be 256 or less than 256. In the case that the number of the outer connection terminals 121a of the probe card is equal to the total number of the test terminals of the test circuit board connection end of the tester, this means the circuit layout of the test circuit board 1a of the probe card is applied to all the test channels, (for example, 256 or 512 test channels) of the tester. In the case that the number of the outer connection terminals 121a of the probe card is less than the total number of the test terminals of the tester, this means the circuit layout of the test circuit board 1a of the probe card is only applied some of the test channels of the tester.
Therefore, the circuit layout of the test circuit 12a of the probe card is very complicated and the circuit layout of the test circuit 12a of the probe card must be specifically designed in adaptation to the wafer to be tested. Therefore, the total manufacturing cost of the probe card is always very high. The test circuit board 1a cannot be commonly applied to different wafers or products to test the same. Moreover, in order to adapt the test circuit board 1a of the probe card to the specification of the circuit board connection end of a different tester, the volume of the test circuit board 1a cannot be minified. This means that the test circuit board 1a of the probe card must be specifically manufactured in accordance with the specification of the tester and it is impossible to minify the size of the test circuit board 1a to lower the manufacturing cost.